Electrophotographic image forming devices typically use a process cartridge that is detachably mounted in the image forming device. One example of the process cartridge includes a drum cartridge incorporating a photosensitive drum therein, and a developing cartridge detachably mounted on the drum cartridge. The developing cartridge includes a developing roller that is urged toward the photosensitive drum by a pressure member. The developing cartridge further includes a toner chamber that accommodates toner therein. To detect an amount of toner remaining in the toner chamber, a toner amount detector is provided to the image forming device.
This type of process cartridge is advantageous in terms of cost, because the drum cartridge and the developing cartridge can be separately and independently replaced with new one. However, such an image forming device is disadvantageous in some points. For example, space for accommodating a member to be pressed by the pressure member is limited.